<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <script>
        let p1 = new Promise((resolve,reject)=>{
            resolve(520)
        })
        let p2 = new Promise((resolve,reject)=>{
            resolve(521)
        })
        let p3 = Promise.resolve('521');
        let res = Promise.all([p1,p2,p3]); // [520, 521 ,'521]

        // let p3 = Promise.reject('521');  // '521'
        console.log(res)
    </script>
</body>
</html>